﻿98 
  Geological 
  Survey 
  of 
  Louisiana 
  [Sect. 
  

  

  considered, 
  characteristic 
  outcrops 
  of 
  the 
  materials 
  of 
  the 
  Grand 
  

   Gulf 
  group, 
  viz. 
  ; 
  solid 
  greenish 
  clays 
  and 
  jagged 
  clay 
  sandstones. 
  

  

  East 
  of 
  the 
  Mississippi 
  Hopkins 
  has 
  mapped 
  as 
  Grand 
  Gulf 
  

   almost 
  all 
  the 
  hill-lands 
  of 
  the 
  Florida 
  parishes. 
  The 
  Grand 
  

   Gulf 
  is 
  here 
  deeply 
  covered 
  with 
  deposits 
  of 
  Lafayette 
  material, 
  

   and 
  exposures 
  have 
  been 
  noted 
  in 
  but 
  few 
  places. 
  Hilgard 
  

   reports 
  the 
  Grand 
  Gulf 
  along 
  the 
  river 
  front 
  as 
  far 
  south 
  as 
  

   Tunica 
  bend.* 
  Two 
  miles 
  northeast 
  of 
  Laurel 
  Hill 
  McGee 
  

   found 
  an 
  exposure 
  of 
  Grand 
  Gulf 
  in 
  the 
  west 
  fork 
  of 
  Thomp- 
  

   son's 
  creek. 
  f 
  So 
  far 
  as 
  we 
  know 
  these 
  are 
  the 
  only 
  exposures 
  

   of 
  Grand 
  Gulf 
  which 
  have 
  been 
  reported, 
  in 
  Louisiana, 
  east 
  of 
  

   the 
  Mississippi 
  ; 
  indeed, 
  Clendenin 
  states 
  that 
  the 
  Mississippi 
  is 
  

   the 
  onh^ 
  stream 
  which 
  has 
  succeeded 
  in 
  cutting 
  through 
  the 
  

   Lafayette 
  and 
  exposing 
  the 
  underlying 
  Grand 
  Gulf. 
  

  

  Thickness. 
  — 
  Hopkins 
  calculates 
  the 
  thickness 
  of 
  the 
  Grand 
  

   Gulf 
  in 
  the 
  vicinity 
  of 
  Harrisonburg 
  at 
  182 
  feet 
  and 
  remarks 
  that 
  

   this 
  is 
  probably 
  less 
  than 
  the 
  true 
  thickness 
  of 
  the 
  deposit. 
  J 
  

   Some 
  of 
  the 
  hills 
  on 
  Bayou 
  Toro 
  are 
  barometrically 
  from 
  250 
  to 
  

   300 
  feet 
  high 
  and 
  hence 
  we 
  feel 
  quite 
  safe 
  in 
  assuming 
  for 
  the 
  

   Grand 
  Gulf 
  a 
  thickness 
  of 
  at 
  least 
  300 
  feet. 
  

  

  Fossils 
  — 
  These 
  beds 
  have 
  not 
  yet 
  yielded, 
  in 
  Louisiana, 
  anj' 
  

   trace 
  of 
  animal 
  remains. 
  Specimens 
  of 
  silicified 
  wood 
  have 
  been 
  

   found 
  at 
  a 
  number 
  of 
  places, 
  || 
  and 
  beds 
  containing 
  twigs 
  and 
  

   leaves 
  have 
  also 
  been 
  reported. 
  Veatch 
  has 
  obtained 
  very 
  good 
  

   impressions 
  of 
  leaves 
  about 
  two 
  miles 
  west 
  of 
  Hornbeck. 
  

   Specimens 
  of 
  silicified 
  palm-wood 
  collected 
  by 
  Johnson 
  in 
  Rapides 
  

   parish 
  have 
  been 
  identified 
  by 
  Knowltou 
  as 
  Palmoxylon 
  que7is- 
  

   tedti2in^ 
  P.cellulosum. 
  Johnson 
  called 
  them 
  Pliocene; 
  McGee 
  

   says 
  they 
  are 
  of 
  Grand 
  Gulf 
  age 
  ; 
  Kuowlton 
  thinks 
  the 
  age 
  very 
  

   uncertain. 
  § 
  

  

  Age 
  of 
  the 
  Grand 
  Gulf 
  

  

  Results 
  of 
  work 
  in 
  Alabama 
  and 
  Florida. 
  — 
  It 
  thus 
  appears 
  that 
  

   no 
  clue 
  to 
  the 
  age 
  of 
  the 
  Grand 
  Gulf 
  is 
  given 
  by 
  the 
  Louisiana 
  

  

  * 
  Am. 
  Jour. 
  Sci. 
  3d 
  Series, 
  vol. 
  i, 
  1871, 
  p. 
  236. 
  

  

  t 
  12 
  An. 
  Rept. 
  U. 
  S. 
  Geol. 
  Surv. 
  part 
  I, 
  p. 
  432. 
  

  

  X 
  2d 
  An. 
  Rept. 
  La. 
  Geol. 
  Surv., 
  187 
  1, 
  p. 
  19. 
  

  

  II 
  Hopkins 
  istAn. 
  Rept. 
  La. 
  Geol. 
  Surv., 
  1870, 
  p. 
  100. 
  

  

  ^ 
  Proc. 
  U. 
  S. 
  Nat. 
  Mus., 
  vol. 
  11, 
  pp. 
  89-91, 
  pi. 
  30, 
  1888. 
  

  

  